考虑土体非均质性和孔隙水压力耦合作用的地下连续墙槽壁稳定性研究

hfcsust@csust.edu.cn。Stability of slurry trench walls considering coupling effects of soil heterogeneity and pore water pressure

针对非均质和富水地层中地下连续墙成槽施工诱发槽壁坍塌失稳的发生机理和破坏模式研究尚不透彻这一现状,利用空间离散技术构建了地下连续墙槽壁极限状态下的三维离散型破坏机制。基于该破坏机制和极限分析上限定理,通过将土体非均质特性和孔隙水压力引入内外能耗功率计算获得了极限状态下槽壁的安全系数目标函数。利用非线性规划算法对该目标函数进行优化计算,得到了地下连续墙槽壁安全系数的最优上限解。为了验证该方法的有效性,将计算得到的槽壁安全系数分别与已有计算结果以及数值模拟结果进行了对比分析,对比结果表明:该方法计算的安全系数与已有计算结果和数值模拟结果基本一致。在此基础上,考虑土体非均质特性和孔隙水压力的耦合作用对地下连续墙槽壁的安全系数进行了参数分析,分析结果表明:孔隙水压力和土体非均质性对地下连续墙槽壁安全系数有较大影响,地下连续墙槽壁安全系数随地下水位高度Hw的升高和黏聚力非均质系数kc的增大而减小,随重度非均质系数kg的增大而增大。

Because the studies on the occurrence mechanism and collapse mode of slurry trench during the construction of underground diaphragm wall in heterogeneous and water-rich stratum are rare,a discretization three-dimensional failure mechanism of slurry trench is established by using the spatial discretization technique.Based on the proposed mechanism and the upper bound theorem of limit analysis,an objective function for the safety factor of the slurry trench is obtained by introducing the heterogeneous characteristics of soil and pore water pressure into the energy dissipation calculation.The optimal upper bound solution for the safety factor of the slurry trench is calculated by the nonlinear programming approach.To verify the validity of the proposed method,the safety factors of the slurry trench are compared with the results of the existing documents and the solutions provided by the numerical simulation technique.Moreover,the comparative results show that the calculated safety factors are in accordance with those of the existing documents and numerical simulations.The parametric analysis shows that the heterogeneous characteristics of soil and pore water pressure affect the safety factor of the slurry trench.The safety factors of the slurry trench decrease with the increase of the cohesive inhomogeneity coefficient kc and underground water level Hw,and increase with the increase of the unit weight inhomogeneity coefficient kg.